In the previous two articles of this series we began describing how to use Windows PowerShell to implement Windows NIC Teaming on a virtual machine running on a Hyper-V host. We also examined what happened when one member of the team failed. This present article examines some additional considerations when implementing Windows NIC Teaming in a virtual machine.

Quick Review

As a quick review, our test environment has a virtual machine named SRV35 running on a Hyper-V host. Both the host and guest operating systems are Windows Server 2012 R2.

The host has two physical network adapters that provide Internet connectivity. The host also has four Hyper-V virtual switches configured, two of which are of the external type while the other two are internal and private.

The virtual machine has four virtual network adapters installed, each of which is assigned to a different virtual switch on the host.

The following table summarizes the network configurations of the Hyper-V host and virtual machine:

Name of virtual network adapter

Virtual switch assigned to adapter

Type of virtual switch

Ethernet

vSwitch-1

External

Ethernet 2

vSwitch-PRI

Private

Ethernet 3

vSwitch-INT

Internal

Ethernet 4

vSwitch-2

External

Table 1

Considerations when adding team members

Recall that we previously used the New-NetLbfoTeam to create a new NIC team in the virtual machine. This team has two members (Ethernet and Ethernet 4) and each of these members is assigned to a different external virtual switch on the host.

Let’s start by using the Get-NetLbfoTeam and Get-NetLbfoTeamMember cmdlets to verify that both team members are active:

Let’s now try adding a third member to our team. We’ll use the virtual network adapter named “Ethernet 2” for this purpose, and we’ll use the Add-NetLbfoTeamMember cmdlet to try to add this virtual network adapter to our team in the virtual machine:

Once again we see an exception, this time with a failure reason of: The only valid LoadBalancingAlgorithms in a Virtual Machine are ‘TransportPorts’, ‘IPAddresses’, and ‘MacAddresses’

The above examples indicate two other important considerations when implementing NIC teaming inside a virtual machine:

Switch Independent is the only supported teaming mode when you implement NIC teaming in a virtual machine. You cannot use Static Teaming or LACP as a teaming mode for teamed virtual network adapters.

Address Hash is the only supported load balancing mode when you implement NIC teaming in a virtual machine. You cannot use Hyper-V Port as a load balancing mode for teamed virtual network adapters.

In addition, we can see from the second example above that Address Hash load balancing can be configured using PowerShell to utilize one of three different kinds of hashing methods:

TCP Ports Uses the source and destination TCP ports and also the source and destination IP addresses as inputs for the hashing function. Note that this is the default hashing method when Address Hash is selected in the NIC Teaming GUI as the load balancing mode for the team.

IP Addresses Uses only the source and destination IP addresses as inputs for the hashing function.

MAC Addresses Uses only the source and destination MAC addresses as inputs for the hashing function.

In some scenarios the particular form of traffic being routed by the team may not support TCP Ports as a hashing method. An example of this would be IPsec traffic. In this case, the hashing method falls back to the IP Address hash method. And if the traffic is not even IP traffic, the hashing method falls back to the MAC Address hash method.

Conclusion

The next and final article in this series will describe some additional considerations when implementing NIC teaming in both physical and virtual environments.

If you would like to read the other parts in this article series please go to:

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Mitch Tulloch

Mitch Tulloch is a widely recognized expert on Windows Server and cloud technologies who has written more than a thousand articles and has authored or been series editor for over 50 books for Microsoft Press. He is a twelve-time recipient of the Microsoft Most Valuable Professional (MVP) award in the technical category of Cloud and Datacenter Management.

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Windows NIC Teaming using PowerShell (Part 7)

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